Fix various QML warnings

CURA-8979

resources/qml/Preferences/Materials/MaterialsDetailsPanel.qml

@@ -60,7 +60,7 @@ Item
 
         properties: materialProperties
         containerId: currentItem != null ? currentItem.id : ""
-        currentMaterialNode: currentItem.container_node
+        currentMaterialNode: currentItem != null ? currentItem.container_node: null
     }
 
     QtObject

resources/qml/Preferences/Materials/MaterialsPage.qml

@@ -68,7 +68,7 @@ UM.ManagementPage
     }
 
     title: catalog.i18nc("@title:tab", "Materials")
-    detailsPlaneCation: currentItem.name
+    detailsPlaneCation: currentItem ? currentItem.name: ""
     scrollviewCaption: catalog.i18nc("@label", "Materials compatible with active printer:") + `<br /><b>${Cura.MachineManager.activeMachine.name}</b>`
 
     buttons: [

resources/qml/Preferences/Materials/MaterialsView.qml

@@ -97,7 +97,6 @@ Item
         }
         border.width: UM.Theme.getSize("default_lining").width
         border.color: UM.Theme.getColor("thick_lining")
-        visible: base.hasCurrentItem
 
         ScrollView
         {
@@ -240,11 +239,12 @@ Item
 
                             anchors.verticalCenter: parent.verticalCenter
 
-                            width: childrenRect.width + 2 * UM.Theme.getSize("narrow_margin").width
-                            height: childrenRect.height + 2 * UM.Theme.getSize("narrow_margin").height
+                            width: colorSelectorBackground.width + 2 * UM.Theme.getSize("narrow_margin").width
+                            height: colorSelectorBackground.height + 2 * UM.Theme.getSize("narrow_margin").height
 
                             Rectangle
                             {
+                                id: colorSelectorBackground
                                 color: properties.color_code
                                 width: UM.Theme.getSize("icon_indicator").width
                                 height: UM.Theme.getSize("icon_indicator").height

resources/themes/cura-light/theme.json

@@ -559,7 +559,7 @@
         "medium_button_icon": [2, 2],
 
         "context_menu": [20, 2],
-        
+
         "icon_indicator": [1, 1],
 
         "printer_status_icon": [1.0, 1.0],